Fastener for lightweight concrete panel and panel assembly

ABSTRACT

The lightweight concrete panel is comprised of a thin concrete slab, a standard stud frame, optional insulation strips to increase its thermal performance for exterior wall applications, and specially engineered blind rivets or screws that connects the thin concrete slab to the metal frame. The specially engineered blind rivet has a protruding and shaped head that can act as an anchor when embedded in the hardened concrete slab and has an optional elastic cover in its embedded head to allow slight movement of the concrete slab. The engineered screw with an elastic cover can also be used as the connecting device that allow slight movement of the concrete slab.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to lightweight concrete panel with asupporting steel frame and the device that connects the concrete facingto the steel frame.

2. Description of the Related Art

The following patents define the current state of the art:

Schilger, U.S. Pat. No. 4,602,467 describes a building panel with asupporting steel frame attached to a concrete slab. The attachingmechanism that connects the steel frame to the concrete slab is part ofthe stud members. The flange of one side of the stud member is punchedand modified in various shapes intending to act as anchor when itsentire side is embedded into the concrete slab. Because of the stud'sflange embedment into the concrete, the panel is considered a compositepanel where both the concrete layer and the steel frame plays importantrole on carrying load.

Schilger, U.S. Pat. No. 4,885,884 describes a building panel with asupporting steel frame attached to a concrete slab. The attachingmechanism that connects the steel frame to the concrete slab is part ofthe stud members. The attaching device of this panel is not one longsection extending one whole side of the stud member like his earlier artU.S. Pat. No. 4,602,467. Instead, the multiple connecting devices arethe intermittingly punched and bent portions in the C-section stud'sflange. The punched and bent sections can be L-shaped, V-shaped, andT-shaped sections that run parallel to the stud member and extend intothe concrete slab, acting as the connecting devices.

Ruiz, U.S. Pat. No. 6,151,858 has a similar concept as Schilger in U.S.Pat. No. 4,885,884. Ruiz's intermittingly punched and bent sections inthe stud's flange have a different shape and bent direction. Ruiz'sprotruding L-shaped is narrower than Schilger and bent differently. LikeSchilger's protruding sections, Ruiz's punched tabs are the connectingdevices that are part of the stud member.

Bodnar, U.S. Pat. No. 4,909,007 has a similar concept as Schilger, U.S.Pat. No. 4,602,467. One entire side of the C-section stud is punched andbent into one L-shaped flange, forming one long integrated attachingdevice to be embedded into a concrete slab. The differences in Bodnar'sart are the openings in the embedded L-shaped junction flange and thelarge opening in the stud web area. The openings in the embeddedjunction flange are claimed to enable material to flow through and forma stronger concrete in the local region. The large openings in the studweb are meant to limit the thermal conductivity from one side to theother through reducing the thermal pathway or steel area in the studweb.

There are three major problems that associate with all mentioned arts:first is that they will need specially designed machinery to create suchspecial stud with integrated connecting mean; second is their poorthermal performance; and third is the meeting of the building codespecifications. Generally, the cost of specially engineered machinery toproduce such modified stud is expensive and prohibiting. The thermalperformance of Ruiz's and Schilger's wall panels is poor due to thedirect material contact between the stud flange and the exteriorconcrete slab. Metal has high temperature conductivity and the heat fromthe exterior concrete flows right though the metal material of the studto the inside stud flange. Although Bodnar's opened web stud is animprovement in reducing thermal conductivity in the stud web, the costof machinery that produces the openings in stud web is expensive andprohibiting due to its complex process. Bodnar's opened web stud is animprovement, but the bottom and top tracks in his steel frame still havesolid web so the panel still has poor thermal performance in those areasof the panel. In load-bearing applications, Bodnar and Schilger's wallpanel will not meet the current International Building Codespecifications in many parts of the country and the world. Little isknown about the composite action between the concrete slab and the steelframe in their design. There is no guidance in the code specificationsto cover such panel constructions. Assuming any unique composite panelis tested and proven to have structural properties, the submitting ofits data and getting it specified in the code specifications can be avery long and costly process. The wide adoption of any unique compositepanel is very unlikely because code specifications are written toencompass a type of construction not of any specific product. Previousarts overlooked these three major issues. The present invention wasdeveloped to overcome these major problems inherent in all prior arts.

SUMMARY OF THE INVENTION

This invention is of a panel construction and the unique components thatmake it. The lightweight concrete panel is comprised of a thin concreteslab, a standard stud frame that can be load-bearing or non-load-bearingthat is well studied and known to be in International Building Codespecifications, optional insulation strips to increase its thermalperformance for exterior wall applications, and unique blind rivet orscrew that connects the thin concrete slab to the metal frame.

The standard steel studs in the supporting frame are manufactured byordinary roll former or automated roll former with rivet or screw holespunched in stud flange. The optional insulation strip is ⅛″ to 1″ thick,extruded foam strip with adhesive backing. The insulating foam can bemade from different materials to have the desired insulating properties.Some rigidity is preferred for easy handling during manufacturingprocess. The insulating strip can have marking or pre-punch holes thatwill align with the hole in the stud flange for easy installation. Thespecially designed blind rivet with extending body is the preferredconnecting device that connects the concrete slab to the supportingsteel frame. The steel stud frame can have steel shear bracing in theinterior side of the frame to meet shear load requirements as specifiedin building code specifications.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates the basic construction of present invention with itscomponents.

FIG. 2 illustrates the unique blind rivet as a separate connectingdevice that connects concrete slab to the steel frame.

FIG. 3 illustrates a cross-section of the blind rivet shown in FIG. 2.

FIG. 4 illustrates a cross-section of an exterior wall panel shown inFIG. 1 with its components.

FIG. 5 illustrates a cross-section of an interior panel where theinsulating strip is unnecessary.

FIG. 6 illustrates a cross-section of an interior panel where a tamperedhead screw with elastic sleeve is the connecting device.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 illustrates an embodiment of the invention very well. Theconcrete panel (1) is comprised of a standard steel stud frame (20) withpre-punch holes (21) for concrete-to-stud connectors in each standardC-section stud (22), a thin ordinary concrete slab with steel meshreinforcement or a very thin ECC (engineered cementitious composite)concrete with high amount of micro fibers as the primary reinforcement(10), optional insulating strips (30) made of various extrudablematerials with high insulating property in exterior wall application,optional steel shear bracing (23) in the interior side of the frame (20)when load-bearing is required, and the specially designed blind rivet(40) as the preferred connecting device that connects the concrete slab(10) to the steel studs (22) of the steel frame (20).

The usage of standard shaped stud (22) of heavy gauge steel and size andsteel shear bracing (23) in the steel frame (20) will allow the panel tomeet the building code specifications readily and will require nospecialized machinery or additional machine to modify the stud flange.The blind rivets or screws (40) attached to the standard studs are notdesigned to carry the bulk of the panel's shear load. The steel shearbracing (23) of the wall panel (1) is designed to be the main support inload-bearing applications. Also, in utilizing the standard stud framesystem, one can use the latest labor-saving technology like automatedroll forming technology from FRAMECAD Group (a New Zealand company) toimprove in the stud frame manufacturing process at relatively low cost.The preferred manufacturing process would require an automated rollformer that can cut to size both studs and tracks, and punch holes forrivets (40) in each stud. When this technology is applied, complexity ofprocess and labor cost is greatly reduced.

The insulating strip (30) is designed to limit the thermal conductivityin the stud flange area. Its has the width of the stud flange, thicknessbetween 1/16″ to 1″, made of various insulating materials, has adhesivebacking, and has enough rigidity to counter the weight pressure of theconcrete slab when the panel is lifted or moved. In exteriorapplications, this insulating strip will greatly increase the panel'sthermal performance. The preferred strip (30) can be extruded rigid foamand has pre-punched holes or marking on strip surface for connectorrivets (40) to go through.

The preferred concrete-to-steel connecting device in the embodied panelis the special designed blind rivet (40). The blind rivet (40) has aprotruding and modified rivet head (41) that allows it to anchor in theconcrete and has an optional rivet cover (43) over the rivet head (41).The protruding rivet head (41) can have various shapes that allow it toact as an anchor in the hardened concrete. The simplest rivet head (41)shape is of a cone shape as shown in FIG. 3 and FIG. 4. The rivet cover(43) is made from various thermal plastic or elastic materials such assilicon or rubber. The usage of various thermal plastic covers in steelanchor is a general practice to help reduce the steel corrosion andreduce a little of thermal conductivity between the steel body and theconcrete. The protective cover (43) may not be necessary if the rivethead (41) is made of stainless steel and the concrete slab (10) issufficiently restrained with steel mesh reinforcement in standardconcrete. However, when the concrete slab (10) is made of ECC(engineered cementitious composite) concrete and has only micro-fiber asthe primary means of reinforcement dry shrinkage of the concretematerial causes the concrete slab (10) to shrink and move slightly. Therivet cover (43) is necessary and it must be made of an elastic materialwith the firmness and thickness to allow the concrete slab or plate (10)to move and reduce any internal stress of the concrete slab (10). If theshrinking concrete slab (10) is restrained the internal stress willcrack concrete slab (10). This usage of elastic cover in any type ofconcrete anchor is novel and necessary to reduce internal stress of theconcrete slab (10). The blind rivet (40) is the preferred connectingdevice because it has greater pull strength or holding strength and itis easier and faster to install. In cases, where the hold strength ofconnecting device is not critical and the concrete slab (10) has slightshrinkage movement, the modified head screw (50) with the elasticcovering (51) can be used as illustrated in FIG. 6.

1. A lightweight and thermal efficient concrete panel comprising: (a) aconcrete slab; (b) a standard metal stud frame with a plurality ofparallel spaced apart steel stud members; (c) insulating strips withadhesive backing; and (d) specially engineered blind rivets orengineered screws with elastic cover as the concrete-to-frame connectingdevices.
 2. A lightweight and thermal efficient concrete panel accordingto claim 1 wherein the insulating strips with adhesive backing are madeof any extrudable insulating material having thickness at least 1/16″and width equal to or greater than the stud flange.
 3. A lightweight andthermal efficient concrete panel according to claim 1 wherein the metalstud members of the standard metal stud frame are the standard C-sectionor U-section studs with pre-punched holes for blind rivets or screws togo through.
 4. A lightweight and thermal efficient concrete panelaccording to claim 1 wherein the engineered blind rivet is made of anytype of steel, has a protruding and shaped head to act as anchorembedded in the concrete slab, and has an optional elastic cover overits head that allows the concrete slab to move slightly.
 5. Alightweight and thermal efficient concrete panel according to claim 1wherein the engineered screw has an elastic cover over its embedded headto allow slight movement of the concrete slab.
 6. A lightweight concretepanel comprising: (a) a concrete slab; (b) a standard metal stud framewith a plurality of parallel spaced apart steel stud members; and (c)specially engineered blind rivets or engineered screws with elasticcovers as the concrete-to-frame connecting devices.
 7. A lightweightconcrete panel according to claim 6 wherein the metal stud members ofthe standard metal stud frame are the standard C-section or U-sectionstuds with pre-punched holes for blind rivets or screws to go through.8. A lightweight concrete panel according to claim 6 wherein theengineered blind rivet is made of any type of steel, has a protrudingand shaped head to act as anchor embedded in the concrete slab, and hasan optional elastic cover over its head that allow the concrete slab tomove slightly.
 9. A lightweight concrete panel according to claim 6wherein the engineered screw has an elastic cover over its embedded headto allow slight movement of the concrete slab.
 10. A steel blind rivetused as a concrete-to-steel frame connecting device wherein the rivethas a protruding and shaped head that acts as an anchor when the head isembedded in the concrete.
 11. The blind rivet according to claim 10wherein the rivet has an elastic cover over the embedded head to allowslight movement in the concrete slab.